Abstract: Method and apparatus for retrieving the channel frequency response H(f), the noise N(f), measured at initialization and the signal to noise ratio SNR(f) measured at show time on a per bin basis, in the upstream or downstream direction. Initialization H(f) is used for analyzing the physical copper loop condition between tip and ring. Initialization N(f) is used for analyzing the crosstalk. Showtime SNR(f) is used for analyzing time dependent changes in crosstalk levels and line attenuation. The combination of H(f), N(f) and SNR(f) allows analysis of the line conditions for reaching the maximum data rate of a given loop, scheduling maintenance and plant update.

Abstract: An adaptive DMT modem determines, as part of a startup sequence, subscriber loop conditions. One or more loop condition adaptation operations are then performed to reduce the complexity of the filters employed in the modem, to reduce the power dissipated in the modem, to optimize performance of the modem or to reduce the likelihood of EMI being radiated into the premises of a subscriber.

Abstract: A physical layer protocol is added to retrieve the in-band downstream ADSL channel frequency response H(f), the noise N(f), measured at initialization and the signal to noise ratio SNR(f) measured at show time on a per bin basis. Additionally retrieval of similar in-band information may be provided in the upstream direction. The definition of the message protocol for retrieving during show time the following ATU-R information on a per bin basis: In-band channel frequency response per bin HR(f) measured during the initialization referred back to the receiver tip and ring copper pair by the ARU-R; In-band noise estimation per bin NR(f) during the initialization referred back to the receiver tip and ring copper pair by the ATU-R; and the signal-to-noise ratio per bin SNRR(f) during show time referred back to the receiver tip and ring copper pair by the ATU-R. The values of SNRR(f) should be updated as they change.

Abstract: A method and apparatus for adjusting the amplitude of a received discrete multi-tone analog signal contaminated by radio frequency interference from radio stations in the AM band are described. The amplitude is adjusted by controlling an analog gain controller in order to utilize substantially all of a dynamic input range of an analog-to-digital converter to reduce the quantization noise of the output digital signal. Data discrimination is truly improved and the capacity of usable discrete multi-tone channels is increased.